Polygenic analysis of ammonia-oxidizing bacteria for completely autotrophic nitrogen removal

This study investigated the functional microbial community in a sequencing batch biofilm reactor (SBBR) for completely autotrophic nitrogen removal over nitrite (CANON), and analyzed the phylogenetic relationships of the key bacteria, the aerobic ammonia oxidizing bacteria (AOB), with three different markers genes: 16S rDNA, amoA and hao. The resulting tree topologies from all the markers were inclined to consistence with minor discrepancy. 16S rDNA- and hao-based phylogenetic analyses revealed that AOB for completely autotrophic nitrogen removal were related most closely to Nitrosomonas sp., and amoA-based phylogenetic analysis demonstrated AOB had highest similarity with a group of uncultured bacteria, while 88 to 94% similarity with Nitrosomonas sp. was also achieved. Generally, the detection of three different markers revealed that AOB were closely related to the bacteria of Proteobacteria Nitrosomonas. This study shows that each of the functional markers (16S rDNA, amoA and hao) could be used to trace AOB for completely autotrophic nitrogen removal and it is more accurate if more than two markers are used at a time.   Key words: 16S rDNA; amoA, completely autotrophic nitrogen removal; hao; phylogenetic analysis.